console: use 'label' argument for time and timeEnd

Turns out the argument is actually called label in the console spec,
while being wrongly named on MDN. This reverts commit
8c043c1245.

MDN has been updated in:

https://developer.mozilla.org/en-US/docs/Web/API/Console/timeEnd$compare?locale=en-US&to=947893&from=918571
https://developer.mozilla.org/en-US/docs/Web/API/Console/time$compare?locale=en-US&to=947891&from=896987

PR-URL: https://github.com/nodejs/node/pull/3590
Reviewed-By: targos - Michaël Zasso <mic.besace@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

doc/api/console.markdown

@@ -72,18 +72,18 @@ object. This is useful for inspecting large complicated objects. Defaults to
 - `colors` - if `true`, then the output will be styled with ANSI color codes.
 Defaults to `false`. Colors are customizable, see below.
 
-### console.time(timerName)
+### console.time(label)
 
 Starts a timer that can be used to compute the duration of an operation. Timers
 are identified by a unique name. Use the same name when you call
-[`console.timeEnd()`](#console_console_timeend_timername) to stop the timer and
+[`console.timeEnd()`](#console_console_timeend_label) to stop the timer and
 output the elapsed time in milliseconds. Timer durations are accurate to the
 sub-millisecond.
 
-### console.timeEnd(timerName)
+### console.timeEnd(label)
 
 Stops a timer that was previously started by calling
-[`console.time()`](#console_console_time_timername) and prints the result to the
+[`console.time()`](#console_console_time_label) and prints the result to the
 console.
 
 Example:

lib/console.js

@@ -55,19 +55,19 @@ Console.prototype.dir = function(object, options) {
 };
 
 
-Console.prototype.time = function(timerName) {
+Console.prototype.time = function(label) {
-  this._times.set(timerName, process.hrtime());
+  this._times.set(label, process.hrtime());
 };
 
 
-Console.prototype.timeEnd = function(timerName) {
+Console.prototype.timeEnd = function(label) {
-  var time = this._times.get(timerName);
+  var time = this._times.get(label);
   if (!time) {
-    throw new Error('No such timer name: ' + timerName);
+    throw new Error('No such label: ' + label);
   }
   const duration = process.hrtime(time);
   const ms = duration[0] * 1000 + duration[1] / 1e6;
-  this.log('%s: %sms', timerName, ms.toFixed(3));
+  this.log('%s: %sms', label, ms.toFixed(3));
 };